It is known that the resveratrol which is a stilbene derivative contained in the grape pericarp is originally a compound having an antibacterial action and present as phytoalexin in which the grape protects oneself from germs and is contained in the grape pericarp regardless of a red type and a white type. It has become increasingly clear by the latest research that the resveratrol has useful effects also to mammals. It is considered that various kinds of bioactive functions including the antioxidation ability of the resveratrol are part of the reason of the useful bioactive effect of red wine which is referred to as a so-called “French paradox”. Furthermore, it has become increasingly clear that the resveratrol has effects on a large number of diseases (Non-patent Document 1). As one of the effects, it has been clarified that the resveratrol has strong anticancer action (Non-patent Document 2). However, edible plants containing the resveratrol are extremely limited and limited to grapes, peanuts, and the like. In the grape, the resveratrol is contained in a high proportion particularly in the grape pericarp but the content is very low and is said to be as low as about 50 to 100 μg/g (Non-patent Document 2).
Then, an approach of increasing the resveratrol concentration in foods has also been performed, and a food obtained by increasing the resveratrol concentration by ultraviolet ray exposure to obtain a resveratrol containing extract, and then adding the extract to a food has been proposed (Patent Document 1). Moreover, as a technique of increasing the intestinal tract absorption efficiency of the resveratrol, an intestinal tract absorption accelerator has also been proposed (Patent Document 2). Thus, the resveratrol is a compound which has extremely excellent properties, such as an anticancer action, an antioxidant action, and an antibacterial action. However, since the resveratrol is a rare component, the cost of products thereof becomes high. Therefore, the resveratrol is commercially available as a supplement and the like but it is hard to be said that the resveratrol fully pervades the society.
On the other hand, as derivatives of the resveratrol, a large number of polymers of the resveratrol have been reported as natural substances, such as s-viniferin (dimer), α-viniferin (trimer), and vaticanol C (tetramer), for example. All the substances are natural rare components similarly as the resveratrol and a technique of supplying these derivatives of the resveratrol in a sufficient amount is not known.
Then, an attempt of producing novel compounds by chemical synthesis referring to the action mechanism of the resveratrol has been made in the pharmaceutical agent field (Non-patent Document 3). However, the novel compounds are development targets mainly as pharmaceutical agents and still have a large number of problems in term of safety.